The term detergency builder can be applied to any component of a detergent composition which increases the detergent power of a surface active agent, hereinafter surfactant. Generally recognized functions of detergency builders include removal of alkaline earth and other undesirable metal ions from washing solutions by sequestration or precipitation, providing alkalinity and buffer capacity, prevention of floculation, maintenance of ionic strength, protection of anionic surfactants from precipitation and extraction of metals from soils as an aid to their removal. Polyphosphates such as tripolyphosphates and pyrophosphates are widely used as ingredients in detergent compositions and are highly effective detergency builders. However, the effect of phosphorus on eutrophication of lakes and streams has been questioned and the use of phosphates in detergent compositions has been subject to government regulation or prohibition.
These circumstances have developed a need for highly effective and efficient phosphorus-free detergency builders. Many materials and combinations of materials have been used or proposed as detergency builders. Carbonates and silicates are widely used in granular detergent compositions, but by themselves are deficient as detergency builders in a number of respects. Aluminosilicates such as described in U.S. Pat. No. 4,274,975, issued June 23, 1981, to Corkill et al., have also been used to replace polyphosphates. Aluminosilicates, however, have relatively low calcium and magnesium binding constants and can present solubility problems, particularly in combination with silicates.
Ether polycarboxylates having one or more units of the structure ##STR1## wherein M is hydrogen, an alkali metal, ammonium or substituted ammonium cation, have been proposed as detergency builder substitutes for polyphosphates. The ether polycarboxylates need not contain phosphorus or nitrogen (also subject to environmental concerns when used in large amounts) and can be more rapidly biodegradable than polymeric polycarboxylates. Ether polycarboxylates are one of the essential components of the present invention.
U.S. Pat. No. 3,293,176, issued Dec. 20, 1966, to White, discloses ether chelating compounds having carboxylic acid, phosphoric acid or sulfonic acids groups.
U.S. Pat. No. 3,692,685, issued Sept. 19, 1972 to Lamberti et al., discloses detergent compositions containing an ether polycarboxylate having the formula: ##STR2## wherein R is H or CH.sub.2 COONa
U.S. Pat. No. 4,228,300, issued Oct. 14, 1980, to Lannert, discloses ether polycarboxylate sequestering agents and detergency builders having the formula ##STR3## wherein M is alkali metal or ammonium, R.sub.1 and R.sub.2 are hydrogen, methyl or ethyl and R.sub.3 is hydrogen, methyl, ethyl or COOM.
U.S. Pat. Nos. 3,923,679, issued Dec. 2, 1975, and 3,835,163, issued Sept. 10, 1974, both to Rapko, disclose 5-membered ring ether carboxylates. U.S. Pat. Nos. 4,158,635, issued June 19, 1979; 4,120,874, issued Oct. 17, 1978, and 4,102,903, issued July 25, 1978, all to Crutchfield et al. disclose 6-membered ring ether carboxylates.
U.S. Pat. No. 3,776,850, issued Dec. 4, 1973, to Pearson et al., discloses polymers to be used as detergent builders having the formula: ##STR4## wherein R is hydrogen or other specified radicals and n is from 2 to about 40, preferably from 2 to about 6.
U.S. Pat. No. 4,146,495, issued Mar. 27, 1979, to Crutchfield et al., incorporated herein by reference, discloses a method of preparing polyacetal carboxylate detergency builders containing the structure ##STR5## wherein M is alkali metal, ammonium, tetralkylammonium or alkanolamine and n averages at least 4.
Many, but not necessarily all, ether polycarboxylates, are deficient in calcium binding power relative to inorganic polyphosphates. This is recognized and modifications to detergent compositions have been suggested to overcome this and other deficiencies. The suggestions include an increase in surfactant level and combination with inorganic alkaline materials such as sodium silicate and sodium carbonate.
It has now been found that ether polycarboxylate materials with a calcium binding constant (expressed as log K.sub.Ca) above a specified minimum value can be successfully incorporated in detergent compositions as part of a builder system comprising three types of organic detergency builders. The resultant detergent compositions provide, in a no or low phosphate composition, fabric cleaning in a household laundry context essentially equivalent to that provided by compositions containing from about 25% to about 50% by weight of an alkali metal polyphosphate such as sodium tripolyphosphate. The additional builders are designated iron and manganese chelating agents and polymeric polycarboxylate dispersing agents herein.